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Effects of carvedilol and metoprolol on the myocardium during mechanical unloading in a rat heterotopic heart transplantation model. Cardiol Young 2021; 31:1269-1274. [PMID: 33745465 DOI: 10.1017/s1047951121000196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND AND OBJECTIVES Left ventricular assist devices enable recovery from severe heart failure and serve as a bridge to heart transplantation. However, chronic mechanical unloading can impair myocardial recovery. We aimed to assess myocyte size, fibrosis, apoptosis, and β-adrenoreceptor levels after rats with left ventricle unloading induced by heterotopic heart transplantation were administered carvedilol and metoprolol. METHODS Thirty rats with heart transplants were divided randomly into control, carvedilol treatment, and metoprolol treatment groups. Follow-up was conducted after 2 and 4 weeks of unloading. RESULTS Carvedilol and metoprolol treatments did not prevent the decrease in myocyte diameter in unloaded left ventricles. Metoprolol significantly decreased the ratio of the fibrotic area in the unloaded heart, measured using Masson's trichrome staining after 2 weeks. However, carvedilol and metoprolol did not reduce apoptosis, based on measurements of terminal deoxynucleotidyl-transferase-mediated dUTP nick end-labelling positive cells and the expression of caspase-3 in unloaded hearts after 2 and 4 weeks. Metoprolol treatment did not significantly decrease the mRNA expression of myocardial SERCA2a in the unloaded heart after 2 weeks. CONCLUSIONS Compared to carvedilol treatment, metoprolol treatment improved myocardial fibrosis and SERCA2a expression to a greater extent; however, neither drug prevented myocardial apoptosis.
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Isovolumic loading of the failing heart by intraventricular placement of a spring expander attenuates cardiac atrophy after heterotopic heart transplantation. Biosci Rep 2018; 38:BSR20180371. [PMID: 29743195 PMCID: PMC6019382 DOI: 10.1042/bsr20180371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/20/2018] [Accepted: 04/30/2018] [Indexed: 12/21/2022] Open
Abstract
Cardiac atrophy is the most common complication of prolonged application of the left ventricle (LV) assist device (LVAD) in patients with advanced heart failure (HF). Our aim was to evaluate the course of unloading-induced cardiac atrophy in rats with failing hearts, and to examine if increased isovolumic loading obtained by intraventricular implantation of an especially designed spring expander would attenuate this process. Heterotopic abdominal heart transplantation (HTx) was used as a rat model of heart unloading. HF was induced by volume overload achieved by creation of the aorto-caval fistula (ACF). The degree of cardiac atrophy was assessed as the weight ratio of the heterotopically transplanted heart (HW) to the control heart. Isovolumic loading was increased by intraventricular implantation of a stainless steel three-branch spring expander. The course of cardiac atrophy was evaluated on days 7, 14, 21, and 28 after HTx Seven days unloading by HTx in failing hearts sufficed to substantially decrease the HW (-59 ± 3%), the decrease progressed when measured on days 14, 21, and 28 after HTx Implantation of the spring expander significantly reduced the decreases in whole HW at all the time points (-39 ± 3 compared with -59 ± 3, -52 ± 2 compared with -69 ± 3, -51 ± 2 compared with -71 ± 2, and -44 ± 2 compared with -71 ± 3%, respectively; P<0.05 in each case). We conclude that the enhanced isovolumic heart loading obtained by implantation of the spring expander attenuates the development of unloading-induced cardiac atrophy in the failing rat heart.
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Heterotopic Abdominal Rat Heart Transplantation as a Model to Investigate Volume Dependency of Myocardial Remodeling. Transplantation 2017; 101:498-505. [PMID: 27906830 DOI: 10.1097/tp.0000000000001585] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Heterotopic abdominal rat heart transplantation has been extensively used to investigate ischemic-reperfusion injury, immunological consequences during heart transplantations and also to study remodeling of the myocardium due to volume unloading. We provide a unique review on the latter and present a summary of the experimental studies on rat heart transplantation to illustrate changes that occur to the myocardium due to volume unloading. We divided the literature based on whether normal or failing rat heart models were used. This analysis may provide a basis to understand the physiological effects of mechanical circulatory support therapy.
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Fu X, Segiser A, Carrel TP, Tevaearai Stahel HT, Most H. Rat Heterotopic Heart Transplantation Model to Investigate Unloading-Induced Myocardial Remodeling. Front Cardiovasc Med 2016; 3:34. [PMID: 27807535 PMCID: PMC5069686 DOI: 10.3389/fcvm.2016.00034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 09/20/2016] [Indexed: 12/17/2022] Open
Abstract
Unloading of the failing left ventricle in order to achieve myocardial reverse remodeling and improvement of contractile function has been developed as a strategy with the increasing frequency of implantation of left ventricular assist devices in clinical practice. But, reverse remodeling remains an elusive target, with high variability and exact mechanisms still largely unclear. The small animal model of heterotopic heart transplantation (hHTX) in rodents has been widely implemented to study the effects of complete and partial unloading on cardiac failing and non-failing tissue to better understand the structural and molecular changes that underlie myocardial recovery. We herein review the current knowledge on the effects of volume unloading the left ventricle via different methods of hHTX in rats, differentiating between changes that contribute to functional recovery and adverse effects observed in unloaded myocardium. We focus on methodological aspects of heterotopic transplantation, which increase the correlation between the animal model and the setting of the failing unloaded human heart. Last, but not least, we describe the late use of sophisticated techniques to acquire data, such as small animal MRI and catheterization, as well as ways to assess unloaded hearts under "reloaded" conditions. While giving regard to certain limitations, heterotopic rat heart transplantation certainly represents the crucial model to mimic unloading-induced changes in the heart and as such the intricacies and challenges deserve highest consideration. Careful translational research will further improve our knowledge of the reverse remodeling process and how to potentiate its effect in order to achieve recovery of contractile function in more patients.
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Affiliation(s)
- Xuebin Fu
- Department of Cardiac and Vascular Surgery, Inselspital University Hospital , Berne , Switzerland
| | - Adrian Segiser
- Department of Cardiac and Vascular Surgery, Inselspital University Hospital , Berne , Switzerland
| | - Thierry P Carrel
- Department of Cardiac and Vascular Surgery, Inselspital University Hospital , Berne , Switzerland
| | | | - Henriette Most
- Department of Cardiac and Vascular Surgery, Inselspital University Hospital , Berne , Switzerland
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Mesenchymal stromal cells improve cardiac function and left ventricular remodeling in a heart transplantation model. J Heart Lung Transplant 2015; 34:1481-8. [DOI: 10.1016/j.healun.2015.05.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 05/02/2015] [Accepted: 05/28/2015] [Indexed: 01/04/2023] Open
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Cecere R, Dowling RD, Giannetti N. Initial clinical experience with the Symphony heart assist system. Ann Thorac Surg 2015; 99:298-301. [PMID: 25555946 DOI: 10.1016/j.athoracsur.2014.07.094] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 05/16/2014] [Accepted: 07/09/2014] [Indexed: 01/29/2023]
Abstract
PURPOSE Current cardiac assist devices provide full support, require a major operation, and function asynchronously to the native heart. In contrast, we developed a novel circulatory support device that provides synchronous partial support and can be placed with a minor operation. We report the first clinical implantation with the Symphony device (Abiomed, Danvers, MA). DESCRIPTION Patients with advanced heart failure despite optimal therapy who had exhausted all options were evaluated. A 64-year-old man with ischemic cardiomyopathy underwent implantation of the Symphony device in the right infraclavicular fossa. EVALUATION After initiating device support, the cardiac index increased from 1.7 to 2.5 L/min/m(2), pulmonary capillary wedge pressure decreased from 26 to 13 mm Hg, right atrial pressure decreased from 12 to 7 mm Hg, creatinine level decreased from 2.3 to 1.5 mg/dL, and New York Heart Association (NYHA) class improved from IIIB to II. CONCLUSIONS Placement of the Symphony device resulted in improvements in hemodynamics and functional status. Further clinical data will help define the role for this approach of partial synchronous support through a less invasive operation in patients with advanced heart failure.
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Affiliation(s)
- Renzo Cecere
- Division of Cardiac Surgery, Department of Surgery, McGill University, Montreal, Quebec, Canada.
| | | | - Nadia Giannetti
- Division of Cardiology, Department of Medicine, McGill University, Montreal, Quebec, Canada
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Liu Y, Maureira P, Gauchotte G, Falanga A, Marie V, Olivier A, Groubatch F, Gu C, Marie PY, Tran N. Effect of chronic left ventricular unloading on myocardial remodeling: Multimodal assessment of two heterotopic heart transplantation techniques. J Heart Lung Transplant 2014; 34:594-603. [PMID: 25703962 DOI: 10.1016/j.healun.2014.11.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 11/05/2014] [Accepted: 11/12/2014] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Cardiac recovery is possible by means of mechanical unloading yet remains rare. Excessive unloading-associated myocardial atrophy and fibrosis may adversely affect the process of reverse remodeling. In this study, we sought to evaluate the effect of different intensities of chronic left ventricular (LV) unloading on myocardial remodeling. METHODS Twenty-five isogenic Lewis rats underwent complete LV unloading (CU, n = 15) induced by heterotopic heart transplantation or partial LV unloading (PU, n = 10) by heterotopic heart-lung transplantation. Information obtained from serial echocardiography, 2-deoxy-2[(18)F]fluoro-d-glucose ((18)F-FDG)-positron emission tomography, and an LV pressure-volume catheter were used to evaluate the morphology, glucose metabolism, and hemodynamic performance of the orthotopic hearts and heterotopic transplants over 4 weeks. Cell size, collagen content, tissue cytokines (interleukin [IL]-1α, IL-2, IL-6, IL-10, tumor necrosis factor-α, and vascular endothelial growth factor), and matrix metalloproteinase-2 and -9 were also determined. The recorded parameters included LV end-systolic dimension, LV end-diastolic dimension, posterior wall thickness, diastolic interventricular septum thickness, LV fractional shortening, and LV ejection fraction. RESULTS We demonstrated an LV load-dependent relationship using echo-based structural (left posterior wall thickness, diastolic interventricular septum thickness, and left ventricular end-diastolic dimension) and functional (LV fractional shortening and LV ejection fraction) parameters, as well as an (18)F-FDG uptake (all p < 0.05). This load-dependent relationship was also evidenced in measurements from the pressure-volume conductance catheter (stroke volume, stroke work, cardiac output, dP/dTmax, and -dP/dTmin; all p < 0.05). Significant myocardial atrophy and fibrosis were observed in unloaded hearts, whereas concentrations of cytokines and matrix metalloproteinases were comparable in both unloading conditions. CONCLUSIONS Partial and complete unloading affected the remodeling of non-failing hearts in a rodent model to different extents on myocardial atrophy, fibrosis, glucose metabolism, and mechanical work. Cardiac atrophy is the prominent change after mechanical unloading, which exaggerates the proportion of total collagen that is responsible for diastolic dysfunction.
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Affiliation(s)
- Yihua Liu
- Department of Cardiovascular Surgery And Heart Transplantation, Centre Hospitalier Universitaire-Nancy, Nancy, France; School of Surgery, Unité Institut National de la Santé et de la Recherche Médicale 1116, Université de Lorraine, Nancy, France; Department of Cardiothoracic Surgery, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Pablo Maureira
- Department of Cardiovascular Surgery And Heart Transplantation, Centre Hospitalier Universitaire-Nancy, Nancy, France; School of Surgery, Unité Institut National de la Santé et de la Recherche Médicale 1116, Université de Lorraine, Nancy, France.
| | | | - Aude Falanga
- School of Surgery, Unité Institut National de la Santé et de la Recherche Médicale 1116, Université de Lorraine, Nancy, France
| | - Venessa Marie
- School of Surgery, Unité Institut National de la Santé et de la Recherche Médicale 1116, Université de Lorraine, Nancy, France
| | | | - Frederique Groubatch
- School of Surgery, Unité Institut National de la Santé et de la Recherche Médicale 1116, Université de Lorraine, Nancy, France
| | - Celine Gu
- Medical Imaging, Centre Hospitalier Universitaire-Nancy, Nancy, France
| | - Pierre-Yves Marie
- School of Surgery, Unité Institut National de la Santé et de la Recherche Médicale 1116, Université de Lorraine, Nancy, France; Medical Imaging, Centre Hospitalier Universitaire-Nancy, Nancy, France
| | - Nguyen Tran
- School of Surgery, Unité Institut National de la Santé et de la Recherche Médicale 1116, Université de Lorraine, Nancy, France
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Myocardial Atrophy and Chronic Mechanical Unloading of the Failing Human Heart. J Am Coll Cardiol 2014; 64:1602-12. [DOI: 10.1016/j.jacc.2014.05.073] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 05/13/2014] [Indexed: 11/20/2022]
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Pokorný M, Cervenka L, Netuka I, Pirk J, Koňařík M, Malý J. Ventricular assist devices in heart failure: how to support the heart but prevent atrophy? Physiol Res 2014; 63:147-56. [PMID: 24779607 DOI: 10.33549/physiolres.932617] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Ventricular assist devices (VAD) have recently established themselves as an irreplaceable therapeutic modality of terminal heart failure. Because of the worldwide shortage of donors, ventricular assist devices play a key role in modern heart failure therapy. Some clinical data have revealed the possibility of cardiac recovery during VAD application. On the other hand, both clinical and experimental studies indicate the risk of the cardiac atrophy development, especially after prolonged mechanical unloading. Little is known about the specific mechanisms governing the unloading-induced cardiac atrophy and about the exact ultrastructural changes in cardiomyocytes, and even less is known about the ways in which possible therapeutical interventions may affect heart atrophy. One aim of this review was to present important aspects of the development of VAD-related cardiac atrophy in humans and we also review the most significant observations linking clinical data and those derived from studies using experimental models. The focus of this article was to review current methods applied to alleviate cardiac atrophy which follows mechanical unloading of the heart. Out of many pharmacological agents studied, only the selective beta2 agonist clenbuterol has been proved to have a significantly beneficial effect on unloading-induced atrophy. Mechanical means of atrophy alleviation also seem to be effective and promising.
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Affiliation(s)
- M Pokorný
- Department of Cardiovascular Surgery, Institute for Clinical and Experimental Medicine, Prague, Czech Republic.
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Brinks H, Giraud MN, Segiser A, Ferrié C, Longnus S, Ullrich ND, Koch WJ, Most P, Carrel TP, Tevaearai HT. Dynamic patterns of ventricular remodeling and apoptosis in hearts unloaded by heterotopic transplantation. J Heart Lung Transplant 2013; 33:203-10. [PMID: 24315785 DOI: 10.1016/j.healun.2013.10.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 09/22/2013] [Accepted: 10/01/2013] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Mechanical unloading of failing hearts can trigger functional recovery but results in progressive atrophy and possibly detrimental adaptation. In an unbiased approach, we examined the dynamic effects of unloading duration on molecular markers indicative of myocardial damage, hypothesizing that potential recovery may be improved by optimized unloading time. METHODS Heterotopically transplanted normal rat hearts were harvested at 3, 8, 15, 30, and 60 days. Forty-seven genes were analyzed using TaqMan-based microarray, Western blot, and immunohistochemistry. RESULTS In parallel with marked atrophy (22% to 64% volume loss at 3 respectively 60 days), expression of myosin heavy-chain isoforms (MHC-α/-β) was characteristically switched in a time-dependent manner. Genes involved in tissue remodeling (FGF-2, CTGF, TGFb, IGF-1) were increasingly upregulated with duration of unloading. A distinct pattern was observed for genes involved in generation of contractile force; an indiscriminate early downregulation was followed by a new steady-state below normal. For pro-apoptotic transcripts bax, bnip-3, and cCasp-6 and -9 mRNA levels demonstrated a slight increase up to 30 days unloading with pronunciation at 60 days. Findings regarding cell death were confirmed on the protein level. Proteasome activity indicated early increase of protein degradation but decreased below baseline in unloaded hearts at 60 days. CONCLUSIONS We identified incrementally increased apoptosis after myocardial unloading of the normal rat heart, which is exacerbated at late time points (60 days) and inversely related to loss of myocardial mass. Our findings suggest an irreversible detrimental effect of long-term unloading on myocardium that may be precluded by partial reloading and amenable to molecular therapeutic intervention.
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Affiliation(s)
- Henriette Brinks
- Department of Cardiac and Vascular Surgery, Inselspital University Hospital, Berne, Switzerland.
| | - Marie-Noelle Giraud
- Cardiology, Department of Medicine, University of Fribourg, Fribourg, Switzerland
| | - Adrian Segiser
- Department of Cardiac and Vascular Surgery, Inselspital University Hospital, Berne, Switzerland
| | - Celine Ferrié
- Department of Cardiac and Vascular Surgery, Inselspital University Hospital, Berne, Switzerland
| | - Sarah Longnus
- Department of Cardiac and Vascular Surgery, Inselspital University Hospital, Berne, Switzerland
| | - Nina D Ullrich
- Institute of Physiology, University of Berne, Berne, Switzerland
| | - Walter J Koch
- Center for Translational Medicine, Department of Pharmacology, Temple University, Philadelphia, Pennsylvania
| | - Patrick Most
- Center for Molecular and Translational Cardiology, Department of Internal Medicine III, University of Heidelberg, Germany
| | - Thierry P Carrel
- Department of Cardiac and Vascular Surgery, Inselspital University Hospital, Berne, Switzerland
| | - Hendrik T Tevaearai
- Department of Cardiac and Vascular Surgery, Inselspital University Hospital, Berne, Switzerland
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The paradox of left ventricular assist device unloading and myocardial recovery in end-stage dilated cardiomyopathy: implications for heart failure in the elderly. Heart Fail Rev 2012; 17:615-33. [DOI: 10.1007/s10741-012-9300-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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12
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Baskin KK, Taegtmeyer H. Taking pressure off the heart: the ins and outs of atrophic remodelling. Cardiovasc Res 2011; 90:243-50. [PMID: 21354996 DOI: 10.1093/cvr/cvr060] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Our work on atrophic remodelling of the heart has led us to appreciate the simple principles in biology: (i) the dynamic nature of intracellular protein turnover, (ii) the return to the foetal gene programme when the heart remodels, and (iii) the adaptive changes of cardiac metabolism. Although the molecular mechanisms of cardiac hypertrophy are many, much less is known regarding the molecular mechanisms of cardiac atrophy. We state the case that knowing more about mechanisms of atrophic remodelling may provide insights into cellular consequences of metabolic and haemodynamic unloading of the stressed heart. Overall we strive to find an answer to the question: 'What makes the failing heart shrink and become stronger?' We speculate that signals arising from intermediary metabolism of energy-providing substrates are likely candidates.
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Affiliation(s)
- Kedryn K Baskin
- Department of Internal Medicine, Division of Cardiology, The University of Texas School of Medicine at Houston, 6431 Fannin, MSB 1.246, Houston, TX 77030, USA
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Right ventricular failure following chronic pressure overload is associated with reduction in left ventricular mass: evidence for atrophic remodeling. J Am Coll Cardiol 2011; 57:921-8. [PMID: 21329838 DOI: 10.1016/j.jacc.2010.08.648] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 07/20/2010] [Accepted: 08/24/2010] [Indexed: 11/21/2022]
Abstract
OBJECTIVES We sought to study whether patients with right ventricular failure (RVF) secondary to chronic thromboembolic pulmonary hypertension (CTEPH) have reduced left ventricular (LV) mass, and whether LV mass reduction is caused by atrophy. BACKGROUND The LV in patients with CTEPH is underfilled (unloaded). LV unloading may cause atrophic remodeling that is associated with diastolic and systolic dysfunction. METHODS We studied LV mass using cardiac magnetic resonance imaging (MRI) in 36 consecutive CTEPH patients (before/after pulmonary endarterectomy [PEA]) and 11 healthy volunteers selected to match age and sex of patients. We studied whether LV atrophy is present in monocrotaline (MCT)-injected rats with RVF or controls by measuring myocyte dimensions and performing in situ hybridization. RESULTS At baseline, CTEPH patients with RVF had significantly lower LV free wall mass indexes than patients without RVF (35 ± 6 g/m(2) vs. 44 ± 7 g/m(2), p = 0.007) or volunteers (42 ± 6 g/m(2), p = 0.006). After PEA, LV free wall mass index increased (from 38 ± 6 g/m(2) to 44 ± 9 g/m(2), p = 0.001), as right ventricular (RV) ejection fraction improved (from 31 ± 8% to 56 ± 12%, p < 0.001). Compared with controls, rats with RVF had reduced LV free wall mass and smaller LV free wall myocytes. Expression of atrial natriuretic peptide was higher, whereas that of α-myosin heavy chain and sarcoplasmic reticulum calcium ATPase-2 were lower in RVF than in controls, both in RV and LV. CONCLUSIONS RVF in patients with CTEPH is associated with reversible reduction in LV free wall mass. In a rat model of RVF, myocyte shrinkage due to atrophic remodeling contributed to reduction in LV free wall mass.
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Muranaka H, Marui A, Tsukashita M, Wang J, Nakano J, Ikeda T, Sakata R. Prolonged mechanical unloading preserves myocardial contractility but impairs relaxation in rat heart of dilated cardiomyopathy accompanied by myocardial stiffness and apoptosis. J Thorac Cardiovasc Surg 2010; 140:916-22. [PMID: 20381089 DOI: 10.1016/j.jtcvs.2010.02.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 01/08/2010] [Accepted: 02/02/2010] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Left ventricular assist devices are used in patients with end-stage dilated cardiomyopathy as a "bridge to recovery." However, physiologic and histologic changes under prolonged mechanical unloading have not been elucidated. Thus, we investigated these changes in the rat heart with dilated cardiomyopathy under mechanical unloading after heterotopic transplantation. METHODS Six weeks after induction of autoimmunized dilated cardiomyopathy in Lewis rats, 2 types of hearts were compared (n = 6 each): (1) an unloaded dilated cardiomyopathy heart (DCM-UL) and (2) a dilated cardiomyopathy heart (DCM). The hearts were evaluated 2 and 4 weeks after transplantation. RESULTS Four weeks after transplantation, developed tension of the papillary muscle (indicator of myocardial contractility) and β-adrenergic response to isoproterenol were better in DCM-UL than in DCM (P = 0.0025 and P <0.0001, respectively). However, half-relaxation time of the papillary muscle (indicator of myocardial relaxation) was worse in the DCM-UL group (P < .0001). The ratio of the fibrotic area of the myocardium and the number of terminal dUTP nick end-labeling-positive myocytes (indicator of myocardial apoptosis) were higher in DCM-UL than in DCM (P = .0072 and P = .0039, respectively). The mRNA expression of collagen Ia was also higher in DCM-UL. CONCLUSIONS Mechanical unloading preserved myocardial contractility and β-adrenergic response but worsened myocardial relaxation. Furthermore, prolonged mechanical unloading has a tendency to increase the ratio of the fibrotic area and myocardial apoptosis. These unfavorable responses, although secondary to prolonged mechanical unloading, may have a negative impact on the bridge to recovery in patients with dilated cardiomyopathy.
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Affiliation(s)
- Hiroyuki Muranaka
- Department of Cardiovascular Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan
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15
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Brinks H, Tevaearai H, Mühlfeld C, Bertschi D, Gahl B, Carrel T, Giraud MN. Contractile function is preserved in unloaded hearts despite atrophic remodeling. J Thorac Cardiovasc Surg 2009; 137:742-6. [PMID: 19258100 DOI: 10.1016/j.jtcvs.2008.09.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Revised: 07/31/2008] [Accepted: 09/06/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Recent studies have shown that mechanically unloading a failing heart may induce reverse remodeling and functional improvement. However, these benefits may be balanced by an unloading-related remodeling including myocardial atrophy that might lead to decrease in function. Using a model of heterotopic heart transplantation, we aimed to characterize the myocardial changes induced by long-term unloading. MATERIAL AND METHODS Macroscopic as well as cellular and functional changes were followed in normal hearts unloaded for a 3-month period. Microscopic parameters were evaluated with stereologic methodology. Myocardial contractile function was quantified with a Langendorff isolated, perfused heart technique. RESULTS Atrophy was macroscopically obvious and accompanied by a 67% reduction of the myocyte volume and a 43% reduction of the interstitial tissue volume, thus accounting for a shift of the myocyte/connective tissue ratio in favor of noncontractile tissue. The absolute number of cardiomyocyte nuclei decreased from 64.7 +/- 5.1 x 10(7) in controls to 22.6 +/- 3.7 x 10(7) (30 days) and 21.6 +/- 3.1 x 10(7) (90 days) after unloading (P < .05). The numeric nucleic density in the unloaded myocardium, as well as the mean cardiomyocyte volume per cardiomyocyte nucleus, remained constant throughout the 90 days of observation. Functional data indicated an increase in ventricular stiffness, although contractile function was preserved, as confirmed by unaltered maximal developed pressure and increased contractility (maximum rate of left ventricular pressure development) and relaxation (minimum rate of left ventricular pressure development). CONCLUSION Atrophic remodeling involves both the myocyte and interstitial tissue compartment. These data suggest that although there is decreased myocardial volume and increased stiffness, contractile capacity is preserved in the long-term unloaded heart.
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Affiliation(s)
- Henriette Brinks
- Department of Cardiovascular Surgery, Inselspital, Berne University Hospital and University of Berne, Berne, Switzerland
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Ahmet I, Krawczyk M, Zhu W, Woo AYH, Morrell C, Poosala S, Xiao RP, Lakatta EG, Talan MI. Cardioprotective and Survival Benefits of Long-Term Combined Therapy with β2 Adrenoreceptor (AR) Agonist and β1 AR Blocker in Dilated Cardiomyopathy Postmyocardial Infarction. J Pharmacol Exp Ther 2008; 325:491-9. [DOI: 10.1124/jpet.107.135335] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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17
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Razeghi P, Volpini KC, Wang ME, Youker KA, Stepkowski S, Taegtmeyer H. Mechanical unloading of the heart activates the calpain system. J Mol Cell Cardiol 2007; 42:449-52. [PMID: 17027024 DOI: 10.1016/j.yjmcc.2006.08.114] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 08/23/2006] [Accepted: 08/29/2006] [Indexed: 11/19/2022]
Abstract
The mechanism for the decrease in cardiomyocyte size with mechanical unloading is unknown. The calpain system regulates cardiomyocyte atrophy. We obtained samples from failing human hearts at the time of implantation and explantation of a left ventricular assist device. For mechanical unloading, we also heterotopically transplanted rat or mouse hearts for 1 week. The effect of calpain inhibition on cardiac atrophy was assessed in transplanted hearts overexpressing calpastatin. We measured transcript levels of calpain 1 and 2 in the human and the rodent model, as well as calpain activity, a calpain-specific degradation product and cardiomyocyte size in the two rodent models. Mechanical unloading of the failing human heart significantly increased calpain 2 gene expression. Transcript levels of calpain 1 and 2, calpain activity and a calpain-specific degradation product all significantly increased in the unloaded rat heart. Unexpectedly, in hearts of animals overexpressing calpastatin, cardiomyocyte size also decreased. Mechanical unloading of the mammalian heart activates the calpain system, although other proteolytic systems may compensate for decreased calpain activity when calpastatin is overexpressed.
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Affiliation(s)
- Peter Razeghi
- Department of Internal Medicine, Division of Cardiology, University of Texas Houston-Medical School, 6431 Fannin, MSB 1.222, Houston, TX 77030, USA
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Razeghi P, Taegtmeyer H. Hypertrophy and Atrophy of the Heart: The Other Side of Remodeling. Ann N Y Acad Sci 2006; 1080:110-9. [PMID: 17132779 DOI: 10.1196/annals.1380.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The size of a cardiomyocyte is determined by relative rates of protein synthesis and degradation. Signaling pathways regulating myocardial protein synthesis have been extensively investigated, not the least because in patients hypertrophy increases cardiovascular morbidity and mortality. Until now strategies to reverse hypertrophy have relied on the inhibition of prohypertrophic signaling pathways. Here we review signaling pathways of atrophy in the heart and we present evidence in support of the idea that activating proatrophic signaling pathways in the presence of prohypertrophic signaling may be an attractive strategy to reverse hypertrophy.
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Affiliation(s)
- Peter Razeghi
- University of Texas Houston Medical School, 6431 Fannin, MSB 1.246, Houston, TX 77030, USA
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Tsuneyoshi H, Oriyanhan W, Kanemitsu H, Shiina R, Nishina T, Matsuoka S, Ikeda T, Komeda M. Does the beta2-agonist clenbuterol help to maintain myocardial potential to recover during mechanical unloading? Circulation 2006; 112:I51-6. [PMID: 16159865 DOI: 10.1161/circulationaha.104.525097] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Chronic mechanical unloading induces left ventricular (LV) atrophy, which may impair functional recovery during support with an LV-assist device. Clenbuterol, a beta2-adrenergic receptor (AR) agonist, is known to induce myocardial hypertrophy and might prevent LV atrophy during LV unloading. Furthermore, beta2-AR stimulation is reported to improve Ca2+ handling and contribute to antiapoptosis. However, there is little information on the effects of clenbuterol during LV unloading. METHODS AND RESULTS We investigated LV atrophy and function after LV unloading produced by heterotopic heart transplantation in isogenic rats. After transplantation, rats were randomized to 1 of 2 groups (n=10 each). The clenbuterol group received 2 mg.kg(-1).d(-1) of the drug for 2 weeks; the control group received normal saline. The weight of unloaded control hearts was 48% less than that of host hearts after 2 weeks of unloading. Clenbuterol significantly increased the weight of the host hearts but did not prevent unloading-induced LV atrophy. Papillary muscles were isolated and stimulated, and there was no difference in developed tension between the 2 groups. However, the inotropic response to the beta-AR agonist isoproterenol significantly improved in the clenbuterol group. The mRNA expression of myocardial sarco(endo)plasmic reticulum Ca2+-ATPase 2a (SERCA2a) and fetal gene shift (myosin heavy chain [MHC] mRNA isozyme) was also significantly improved by clenbuterol treatment. There was no difference in beta1-AR mRNA expression between the 2 groups. In contrast, beta2-AR mRNA was significantly decreased in the clenbuterol-treated, unloaded heart. This indicates that clenbuterol may downregulate beta2-ARs. In the evaluation of apoptosis, mRNA expression of caspase-3, which is the central pathway for apoptosis, tended to be better in the clenbuterol group. CONCLUSIONS During complete LV unloading, clenbuterol did not prevent myocardial atrophy but improved gene expression (SERCA2a, beta-MHC) and beta-adrenergic responsiveness and potentially prevented myocardial apoptosis. However, chronic administration of clenbuterol may be associated with downregulation of beta2-ARs.
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MESH Headings
- Adrenergic beta-Agonists/pharmacology
- Adrenergic beta-Agonists/therapeutic use
- Animals
- Atrophy
- Calcium-Transporting ATPases/biosynthesis
- Calcium-Transporting ATPases/genetics
- Caspase 3
- Caspases/biosynthesis
- Caspases/genetics
- Clenbuterol/pharmacology
- Clenbuterol/therapeutic use
- Down-Regulation/drug effects
- Drug Evaluation, Preclinical
- Enzyme Induction/drug effects
- Gene Expression Regulation/drug effects
- Heart/drug effects
- Heart Transplantation
- Heart Ventricles/drug effects
- Heart Ventricles/pathology
- Heart Ventricles/physiopathology
- Isoproterenol/pharmacology
- Male
- Myocardial Contraction/drug effects
- Myocardium/pathology
- Myosin Heavy Chains/biosynthesis
- Myosin Heavy Chains/genetics
- Organ Size
- Papillary Muscles/drug effects
- Papillary Muscles/physiopathology
- Protein Isoforms/biosynthesis
- Protein Isoforms/genetics
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Random Allocation
- Rats
- Rats, Inbred Lew
- Receptors, Adrenergic, beta-1/biosynthesis
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-2/biosynthesis
- Receptors, Adrenergic, beta-2/drug effects
- Receptors, Adrenergic, beta-2/genetics
- Sarcoplasmic Reticulum Calcium-Transporting ATPases
- Stress, Mechanical
- Transplantation, Heterotopic
- Transplantation, Isogeneic
- Ventricular Function, Left/drug effects
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Affiliation(s)
- Hiroshi Tsuneyoshi
- Department of Cardiovascular Surgery, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
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